The experimental craft, which is covered in 17,000 solar cells, took off from Abu Dhabi in March.

The Pacific crossing, however, was always going to be the most challenging part of this epic journey.

Solar Impulse had already waited more than a month in Nanjing for the right weather conditions to open up over the Pacific.

It needs not only favourable winds to push forward, but also cloud-free skies during the day to soak up enough energy from the Sun to enable nighttime flying on its batteries.

The team's meteorologists thought they had identified a suitable weather window - and the plane set off at 18:39 GMT on Saturday.

Mr Borschberg had been making good progress. However, in the early hours of Monday morning (GMT), the Solar Impulse team announced it was putting the plane in a holding pattern.

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Media captionThe zero-fuel solar-powered plane's first attempt to fly around the world has been postponed due to bad weather. Peter Gibbs explains.

The pilot was asked to circle over the Sea of Japan while meteorologists assessed whether they could find their way through a worsening weather front close to Hawaii.

Mr Borschberg was just hours away from the point of no return - the stage in the flight where, if something were to go wrong, the plane would be too far from land to turn back and Mr Borschberg would have to bail out into the ocean.

The team decided this was not a risk worth taking.

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By the time the craft lands, it will have flown more than 3,000km (1,860 miles) in about 40 hours, which is already the longest flight ever made by a solar-powered airplane in terms of both duration and distance.

While Mr Borschberg waits in Japan, his support team will try to identify another weather window to get to kalaeloa airport in Hawaii.

However, the fear is that further delays could have an impact on later stages of the round-the-world quest.

Ideally, the team needs to cross America, and then the Atlantic, before the hurricane season starts to peak in August.